- Type 1 Diabetes
- Type 2 Diabetes
- Risk Factors
- Blood Sugar Levels
What is diabetes?
Diabetes mellitus is a group of metabolic diseases characterized by high blood sugar (glucose) levels that result from defects in insulin secretion, its action, or both. Diabetes mellitus, commonly referred to as diabetes (as it will be in this article) was first identified as a disease associated with "sweet urine," and excessive muscle loss in the ancient world. Elevated levels of blood glucose (hyperglycemia) lead to spillage of glucose into the urine, hence the term sweet urine.
Normally, blood glucose levels are tightly controlled by insulin, a hormone produced by the pancreas. Insulin lowers the blood glucose level. When the blood glucose elevates (for example, after eating food), insulin is released from the pancreas to normalize the glucose level by promoting the uptake of glucose into body cells. In patients with diabetes, the absence of insufficient production of or lack of response to insulin causes hyperglycemia. Diabetes is a chronic medical condition, meaning that although it can be controlled, it lasts a lifetime.
How many people in the US have diabetes?
- Diabetes affects approximately 30.3 million people (9.4% of the population) in the United States, while another estimated 84.1 million people have prediabetes and don't know it.
- An estimated 7.2 million people in the United States have diabetes and don't even know it.
- Over time, diabetes can lead to blindness, kidney failure, and nerve damage. These types of damage are the result of damage to small vessels, referred to as a microvascular disease.
- Diabetes also is an important factor in accelerating the hardening and narrowing of the arteries (atherosclerosis), leading to strokes, coronary heart disease, and other large blood vessel diseases. This is referred to as macrovascular disease.
- From an economic perspective, the total annual cost of diabetes in 2012 was estimated to be 245 billion dollars in the United States. This included 116 billion in direct medical costs (healthcare costs) for people with diabetes and another 69 billion in other costs due to disability, premature death, or work loss.
- Medical expenses for people with diabetes are over two times higher than those for people who do not have diabetes. Remember, these numbers reflect only the population in the United States. Globally, the statistics are staggering.
- Diabetes is the 7th leading cause of death in the United States listed on death certificates in recent years.
What are the different types of diabetes?
There are two major types of diabetes, called type 1 and type 2. Type 1 diabetes was also formerly called insulin-dependent diabetes mellitus (IDDM), or juvenile-onset diabetes mellitus. In type 1 diabetes, the pancreas undergoes an autoimmune attack by the body itself and is rendered incapable of making insulin. Abnormal antibodies have been found in the majority of patients with type 1 diabetes. Antibodies are proteins in the blood that are part of the body's immune system. The patient with type 1 diabetes must rely on insulin medication for survival.
What is type 1 diabetes?
In autoimmune diseases, such as type 1 diabetes, the immune system mistakenly manufactures antibodies and inflammatory cells that are directed against and cause damage to patients' own body tissues. In persons with type 1 diabetes, the beta cells of the pancreas, which are responsible for insulin production, are attacked by the misdirected immune system. It is believed that the tendency to develop abnormal antibodies in type 1 diabetes is, in part, genetically inherited, though the details are not fully understood.
Exposure to certain viral infections (mumps and Coxsackie viruses) or other environmental toxins may serve to trigger abnormal antibody responses that cause damage to the pancreas cells where insulin is made. Some of the antibodies seen in type 1 diabetes include anti-islet cell antibodies, anti-insulin antibodies, and anti-glutamic decarboxylase antibodies. These antibodies can be detected in the majority of patients and may help determine which individuals are at risk for developing type 1 diabetes.
At present, the American Diabetes Association does not recommend general screening of the population for type 1 diabetes, though screening of high-risk individuals, such as those with a first-degree relative (sibling or parent) with type 1 diabetes should be encouraged. Type 1 diabetes tends to occur in young, lean individuals, usually before 30 years of age; however, older patients do present with this form of diabetes on occasion. This subgroup is referred to as latent autoimmune diabetes in adults (LADA). LADA is a slow, progressive form of type 1 diabetes. Of all the people with diabetes, only approximately 10% have type 1 diabetes and the remaining 90% have type 2 diabetes.
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What is type 2 diabetes?
Type 2 diabetes was also previously referred to as non-insulin-dependent diabetes mellitus (NIDDM), or adult-onset diabetes mellitus (AODM). In type 2 diabetes, patients can still produce insulin but do so relatively inadequately for their body's needs, particularly in the face of insulin resistance as discussed above. In many cases, this actually means the pancreas produces larger than normal quantities of insulin. A major feature of type 2 diabetes is a lack of sensitivity to insulin by the cells of the body (particularly fat and muscle cells).
In addition to the problems with an increase in insulin resistance, the release of insulin by the pancreas may also be defective and suboptimal. In fact, there is a known steady decline in beta cell production of insulin in type 2 diabetes that contributes to worsening glucose control. (This is a major factor for many patients with type 2 diabetes who ultimately require insulin therapy.) Finally, the liver in these patients continues to produce glucose through a process called gluconeogenesis despite elevated glucose levels. The control of gluconeogenesis becomes compromised.
While it is said that type 2 diabetes occurs mostly in individuals over 30 years old and the incidence increases with age, an alarming number of patients with type 2 diabetes are barely in their teen years. Most of these cases are a direct result of poor eating habits, higher body weight, and lack of exercise.
While there is a strong genetic component to developing this form of diabetes, there are other risk factors - the most significant of which is obesity. There is a direct relationship between the degree of obesity and the risk of developing type 2 diabetes, and this holds true in children as well as adults. It is estimated that the chance to develop diabetes doubles for every 20% increase over desirable body weight.
Regarding age, data shows that for each decade after 40 years of age regardless of weight there is an increase in the incidence of diabetes. The prevalence of diabetes in persons 65 years of age and older is around 25%. Type 2 diabetes is also more common in certain ethnic groups. Compared with a 7% prevalence in non-Hispanic Caucasians, the prevalence in Asian Americans is estimated to be 8.0%, in Hispanics at 13%, in blacks around 12.3%, and in certain Native American communities 20% to 50%. Finally, diabetes occurs much more frequently in women with a prior history of diabetes that develops during pregnancy (gestational diabetes).
What are the other types of diabetes?
Diabetes can occur temporarily during pregnancy, and reports suggest that it occurs in 2% to 10% of all pregnancies. Significant hormonal changes during pregnancy can lead to blood sugar elevation in genetically predisposed individuals. Blood sugar elevation during pregnancy is called gestational diabetes. Gestational diabetes usually resolves once the baby is born. However, 35% to 60% of women with gestational diabetes will eventually develop type 2 diabetes over the next 10 to 20 years, especially in those who require insulin during pregnancy and those who remain overweight after their delivery. Women with gestational diabetes are usually asked to undergo an oral glucose tolerance test about six weeks after giving birth to determine if their diabetes has persisted beyond the pregnancy, or if any evidence (such as impaired glucose tolerance) is present that may be a clue to a risk for developing diabetes.
"Secondary" diabetes refers to elevated blood sugar levels from another medical condition. Secondary diabetes may develop when the pancreatic tissue responsible for the production of insulin is destroyed by diseases, such as chronic pancreatitis (inflammation of the pancreas by toxins like excessive alcohol), trauma, or surgical removal of the pancreas.
Diabetes can also result from other hormonal disturbances, such as excessive growth hormone production (acromegaly) and Cushing's syndrome. In acromegaly, a pituitary gland tumor at the base of the brain causes excessive production of growth hormone, leading to hyperglycemia. In Cushing's syndrome, the adrenal glands produce an excess of cortisol, which promotes blood sugar elevation.
Certain medications may worsen diabetes control, or "unmask" latent diabetes. This is seen most commonly when steroid medications (such as prednisone) are taken and also with medications used in the treatment of HIV infection (AIDS).
What causes diabetes?
Insufficient production of insulin (either absolutely or relative to the body's needs), production of defective insulin (which is uncommon), or the inability of cells to use insulin properly and efficiently leads to hyperglycemia and diabetes.
- This latter condition affects mostly the cells of muscle and fat tissues and results in a condition known as insulin resistance. This is the primary problem in type 2 diabetes.
- The absolute lack of insulin, usually secondary to a destructive process affecting the insulin-producing beta cells in the pancreas, is the main disorder in type 1 diabetes.
In type 2 diabetes, there also is a steady decline of beta cells that adds to the process of elevated blood sugars. Essentially, if someone is resistant to insulin, the body can, to some degree, increase the production of insulin and overcome the level of resistance. After a time, if production decreases and insulin cannot be released as vigorously, hyperglycemia develops.
What is glucose?
Glucose is a simple sugar found in food. Glucose is an essential nutrient that provides energy for the proper functioning of the body cells. Carbohydrates are broken down in the small intestine and the glucose in digested food is then absorbed by the intestinal cells into the bloodstream and is carried by the bloodstream to all the cells in the body where it is utilized. However, glucose cannot enter the cells alone and needs insulin to aid in its transport into the cells. Without insulin, the cells become starved of glucose energy despite the presence of abundant glucose in the bloodstream. In certain types of diabetes, the cells' inability to utilize glucose gives rise to the ironic situation of "starvation in the midst of plenty". The abundant, unutilized glucose is wastefully excreted in the urine.
What is insulin?
Insulin is a hormone that is produced by specialized cells (beta cells) of the pancreas. (The pancreas is a deep-seated organ in the abdomen located behind the stomach.) In addition to helping glucose enter the cells, insulin is also important in tightly regulating the level of glucose in the blood. After a meal, the blood glucose level rises. In response to the increased glucose level, the pancreas normally releases more insulin into the bloodstream to help glucose enter the cells and lower blood glucose levels after a meal. When the blood glucose levels are lowered, the insulin release from the pancreas is turned down. It is important to note that even in the fasting state there is a low steady release of insulin than fluctuates a bit and helps to maintain a steady blood sugar level during fasting. In normal individuals, such a regulatory system helps to keep blood glucose levels in a tightly controlled range. As outlined above, in patients with diabetes, the insulin is either absent, relatively insufficient for the body's needs, or not used properly by the body. All of these factors cause elevated levels of blood glucose (hyperglycemia).
What are the risk factors for diabetes?
Risk factors for type 1 diabetes are not as well understood as those for type 2 diabetes. Family history is a known risk factor for type 1 diabetes. Other risk factors can include having certain infections or diseases of the pancreas.
Risk factors for type 2 diabetes and prediabetes are many. The following can raise your risk of developing type 2 diabetes:
- Being obese or overweight
- High blood pressure
- Elevated levels of triglycerides and low levels of "good" cholesterol (HDL)
- Sedentary lifestyle
- Family history
- Increasing age
- Polycystic ovary syndrome
- Impaired glucose tolerance
- Insulin resistance
- Gestational diabetes during a pregnancy
- Ethnic background: Hispanic/Latino Americans, African-Americans, Native Americans, Asian-Americans, Pacific Islanders, and Alaska natives are at greater risk.
What are the early signs and symptoms of diabetes?
- The early symptoms of untreated diabetes are related to elevated blood sugar levels and loss of glucose in the urine. High amounts of glucose in the urine can cause increased urine output (frequent urination) and lead to dehydration.
- Dehydration also causes increased thirst and water consumption.
- A relative or absolute insulin deficiency eventually leads to weight loss.
- The weight loss of diabetes occurs despite an increase in appetite.
- Some untreated diabetes patients also complain of fatigue.
- Nausea and vomiting can also occur in patients with untreated diabetes.
- Frequent infections (such as infections of the bladder, skin, and vaginal areas) are more likely to occur in people with untreated or poorly-controlled diabetes.
- Fluctuations in blood glucose levels can lead to blurred vision.
- Extremely elevated glucose levels can lead to lethargy and coma.
Diagnosis of diabetes
The fasting blood glucose (sugar) test is the preferred way to diagnose diabetes. It is easy to perform and convenient. After the person has fasted overnight (at least 8 hours), a single sample of blood is drawn and sent to the laboratory for analysis. This can also be done accurately in a doctor's office using a glucose meter.
- Normal fasting plasma glucose levels are less than 100 milligrams per deciliter (mg/dl).
- Fasting plasma glucose levels of more than 126 mg/dl on two or more tests on different days indicate diabetes.
- A random blood glucose test can also be used to diagnose diabetes. A blood glucose level of 200 mg/dl or higher indicates diabetes.
When fasting blood glucose stays above 100mg/dl, but in the range of 100-126mg/dl, this is known as impaired fasting glucose (IFG). While patients with IFG or prediabetes do not have the diagnosis of diabetes, this condition carries with it its own risks and concerns and is addressed elsewhere.
The oral glucose tolerance test
Though not routinely used any longer, the oral glucose tolerance test (OGTT) is a gold standard for making the diagnosis of type 2 diabetes. It is still commonly used for diagnosing gestational diabetes and in conditions of pre-diabetes, such as polycystic ovary syndrome. With an oral glucose tolerance test, the person fasts overnight (at least eight but not more than 16 hours). Then first, the fasting plasma glucose is tested. After this test, the person receives an oral dose (75 grams) of glucose. There are several methods employed by obstetricians to do this test, but the one described here is standard. Usually, the glucose is in a sweet-tasting liquid that the person drinks. Blood samples are taken at specific intervals to measure the blood glucose.
For the test to give reliable results:
- The person must be in good health (not have any other illnesses, not even a cold).
- The person should be normally active (not lying down, for example, as an inpatient in a hospital), and
- The person should not be taking medicines that could affect blood glucose.
- On the morning of the test, the person should not smoke or drink coffee.
The classic oral glucose tolerance test measures blood glucose levels five times over a period of three hours. Some physicians simply get a baseline blood sample followed by a sample two hours after drinking the glucose solution. In a person without diabetes, the glucose levels rise and then fall quickly. In someone with diabetes, glucose levels rise higher than normal and fail to come back down as fast.
People with glucose levels between normal and diabetic have impaired glucose tolerance (IGT) or insulin resistance. People with impaired glucose tolerance do not have diabetes but are at high risk for progressing to diabetes. Each year, 1% to 5% of people whose test results show impaired glucose tolerance actually eventually develop diabetes. Weight loss and exercise may help people with impaired glucose tolerance return their glucose levels to normal. In addition, some physicians advocate the use of medications, such as metformin (Glucophage), to help prevent/delay the onset of overt diabetes.
Research has shown that impaired glucose tolerance itself may be a risk factor for the development of heart disease. In the medical community, most physicians now understand that impaired glucose tolerance is not simply a precursor of diabetes, but is its own clinical disease entity that requires treatment and monitoring.
Evaluating the results of the oral glucose tolerance test
Glucose tolerance tests may lead to one of the following diagnoses:
- Normal response: A person is said to have a normal response when the 2-hour glucose level is less than 140 mg/dl, and all values between 0 and 2 hours are less than 200 mg/dl.
- Impaired glucose tolerance (prediabetes): A person is said to have impaired glucose tolerance when the fasting plasma glucose is less than 126 mg/dl and the 2-hour glucose level is between 140 and 199 mg/dl.
- Diabetes: A person has diabetes when two diagnostic tests done on different days show that the blood glucose level is high.
- Gestational diabetes: A pregnant woman has gestational diabetes when she has any two of the following:
- a fasting plasma glucose of 92 mg/dl or more,
- a 1-hour glucose level of 180 mg/dl or more, or
- a 2-hour glucose level of 153 mg/dl, or more.
How do I know if I have diabetes?
Endocrinology is the specialty of medicine that deals with hormone disturbances, and both endocrinologists and pediatric endocrinologists manage patients with diabetes. People with diabetes may also be treated by family medicine or internal medicine specialists. When complications arise, people with diabetes may be treated by other specialists, including neurologists, gastroenterologists, ophthalmologists, surgeons, cardiologists, or others.
- Many people are unaware that they have diabetes, especially in its early stages when symptoms may not be present.
- There is no definite way to know if you have diabetes without undergoing blood tests to determine your blood glucose levels (see the section on Diagnosis of diabetes).
- See your doctor if you have symptoms of diabetes or if you are concerned about your diabetes risk.
Why is blood sugar checked at home?
Home blood sugar (glucose) testing is an important part of controlling blood sugar. One important goal of diabetes treatment is to keep the blood glucose levels near the normal range of 70 to 120 mg/dl before meals and under 140 mg/dl two hours after eating. Blood glucose levels are usually tested before and after meals, and at bedtime. The blood sugar level is typically determined by pricking a fingertip with a lancing device and applying the blood to a glucose meter, which reads the value. There are many meters on the market, for example, Accu-Check Advantage, One Touch Ultra, Sure Step, and Freestyle. Each meter has its own advantages and disadvantages (some use less blood, some have a larger digital readout, some take a shorter time to give you results, etc.). The test results are then used to help patients make adjustments in medications, diets, and physical activities.
There are some interesting developments in blood glucose monitoring including continuous glucose sensors. The new continuous glucose sensor systems involve an implantable cannula placed just under the skin in the abdomen or in the arm. This cannula allows for frequent sampling of blood glucose levels. Attached to this is a transmitter that sends the data to a pager-like device. This device has a visual screen that allows the wearer to see, not only the current glucose reading but also the graphic trends. In some devices, the rate of change in blood sugar is also shown. There are alarms for low and high sugar levels. Certain models will alarm if the rate of change indicates the wearer is at risk for dropping or rising blood glucose too rapidly. One version is specifically designed to interface with their insulin pumps. In most cases, the patient still must manually approve any insulin dose (the pump cannot blindly respond to the glucose information it receives, it can only give a calculated suggestion as to whether the wearer should give insulin, and if so, how much). However, in 2013 the US FDA approved the first artificial pancreas type device, meaning an implanted sensor and pump combination that stops insulin delivery when glucose levels reach a certain low point. All of these devices need to be correlated to fingersticks measurements for a few hours before they can function independently. The devices can then provide readings for 3 to 5 days.
Diabetes experts feel that these blood glucose monitoring devices give patients a significant amount of independence to manage their disease process, and they are a great tool for education as well. It is also important to remember that these devices can be used intermittently with fingerstick measurements. For example, a well-controlled patient with diabetes can rely on fingerstick glucose checks a few times a day and do well. If they become ill, if they decide to embark on a new exercise regimen, if they change their diet, and so on, they can use the sensor to supplement their fingerstick regimen, providing more information on how they are responding to new lifestyle changes or stressors. This kind of system takes us one step closer to closing the loop, and to the development of an artificial pancreas that senses insulin requirements based on glucose levels and the body's needs and releases insulin accordingly - the ultimate goal.
Hemoglobin A1c (HBA1c)
To explain what hemoglobin A1c is, think in simple terms. Sugar sticks, and when it's around for a long time, it's harder to get it off. In the body, sugar sticks too, particularly to proteins. The red blood cells that circulate in the body live for about three months before they die off. When sugar sticks to these hemoglobin proteins in these cells, it is known as glycosylated hemoglobin or hemoglobin A1c (HBA1c). Measurement of HBA1c gives us an idea of how much sugar is present in the bloodstream for the preceding three months. In most labs, the normal range is 4%-5.9 %. In poorly controlled diabetes, it's 8.0% or above, and in well-controlled patients, it's less than 7.0% (optimal is <6.5%). The benefit of measuring A1c is that it gives a more reasonable and stable view of what's happening over the course of time (three months), and the value does not vary as much as finger stick blood sugar measurements. There is a direct correlation between A1c levels and average blood sugar levels as follows.
While there are no guidelines to use A1c as a screening tool, it gives a physician a good idea that someone is diabetic if the value is elevated. Right now, it is used as a standard tool to determine blood sugar control in patients known to have diabetes.
|HBA1c (%)||Mean blood sugar (mg/dl)|
The American Diabetes Association currently recommends an A1c goal of less than 7.0% with an A1C goal for selected individuals as close to normal as possible (<6%) without significant hypoglycemia. Other groups such as the American Association of Clinical Endocrinologists feel that an A1c of <6.5% should be the goal.
Of interest, studies have shown that there is about a 35% decrease in relative risk for microvascular disease for every 1% reduction in A1c. The closer to normal the A1c, the lower the absolute risk for microvascular complications.
It should be mentioned here that there are a number of conditions in which an A1c value may not be accurate. For example, with significant anemia, the red blood cell count is low, and thus the A1c is altered. This may also be the case in sickle cell disease and other hemoglobinopathies.
What are the acute complications of diabetes?
- Severely elevated blood sugar levels due to an actual lack of insulin or a relative deficiency of insulin.
- Abnormally low blood sugar levels due to too much insulin or other glucose-lowering medications.
Acute complications of type 2 diabetes
In patients with type 2 diabetes, stress, infection, and medications (such as corticosteroids) can also lead to severely elevated blood sugar levels. Accompanied by dehydration, severe blood sugar elevation in patients with type 2 diabetes can lead to an increase in blood osmolality (hyperosmolar state). This condition can worsen and lead to coma (hyperosmolar coma). A hyperosmolar coma usually occurs in elderly patients with type 2 diabetes. Like diabetic ketoacidosis, a hyperosmolar coma is a medical emergency. Immediate treatment with intravenous fluid and insulin is important in reversing the hyperosmolar state. Unlike patients with type 1 diabetes, patients with type 2 diabetes do not generally develop ketoacidosis solely on the basis of their diabetes. Since in general, type 2 diabetes occurs in an older population, concomitant medical conditions are more likely to be present, and these patients may actually be sicker overall. The complication and death rates from hyperosmolar coma are thus higher than in diabetic ketoacidosis.
Hypoglycemia means abnormally low blood sugar (glucose). In patients with diabetes, the most common cause of low blood sugar is excessive use of insulin or other glucose-lowering medications, to lower the blood sugar level in diabetic patients in the presence of a delayed or absent meal. When low blood sugar levels occur because of too much insulin, it is called an insulin reaction. Sometimes, low blood sugar can be the result of an insufficient caloric intake or sudden excessive physical exertion.
Blood glucose is essential for the proper functioning of brain cells. Therefore, low blood sugar can lead to central nervous system symptoms such as:
- weakness, and
The actual level of blood sugar at which these symptoms occur varies with each person, but usually, it occurs when blood sugars are less than 50 mg/dl. Untreated, severely low blood sugar levels can lead to coma, seizures, and, in the worst case scenario, irreversible brain death.
The treatment of low blood sugar consists of administering a quickly absorbed glucose source. These include glucose-containing drinks, such as orange juice, soft drinks (not sugar-free), or glucose tablets in doses of 15-20 grams at a time (for example, the equivalent of half a glass of juice). Even cake frosting applied inside the cheeks can work in a pinch if patient cooperation is difficult. If the individual becomes unconscious, glucagon can be given by intramuscular injection.
Glucagon is a hormone that causes the release of glucose from the liver (for example, it promotes gluconeogenesis). Glucagon can be lifesaving and every patient with diabetes who has a history of hypoglycemia (particularly those on insulin) should have a glucagon kit. Families and friends of those with diabetes need to be taught how to administer glucagon since obviously, the patients will not be able to do it themselves in an emergency situation. Another lifesaving device that should be mentioned is very simple; a medic-alert bracelet should be worn by all patients with diabetes.
Acute complications of type 1 diabetes
Insulin is vital to patients with type 1 diabetes - they cannot live without a source of exogenous insulin. Without insulin, patients with type 1 diabetes develop severely elevated blood sugar levels. This leads to increased urine glucose, which in turn leads to excessive loss of fluid and electrolytes in the urine. Lack of insulin also causes the inability to store fat and protein along with a breakdown of existing fat and protein stores. This dysregulation results in the process of ketosis and the release of ketones into the blood. Ketones turn the blood acidic, a condition called diabetic ketoacidosis (DKA). Symptoms of diabetic ketoacidosis include nausea, vomiting, and abdominal pain. Without prompt medical treatment, patients with diabetic ketoacidosis can rapidly go into shock, coma, and even death may result.
Diabetic ketoacidosis can be caused by infections, stress, or trauma, all of which may increase insulin requirements. In addition, missing doses of insulin is also an obvious risk factor for developing diabetic ketoacidosis. Urgent treatment of diabetic ketoacidosis involves the intravenous administration of fluid, electrolytes, and insulin, usually in a hospital intensive care unit. Dehydration can be very severe, and it is not unusual to need to replace 6-7 liters of fluid when a person presents with diabetic ketoacidosis. Antibiotics are given for infections. With treatment, abnormal blood sugar levels, ketone production, acidosis, and dehydration can be reversed rapidly, and patients can recover remarkably well.
What are the chronic complications of diabetes?
These diabetes complications are related to blood vessel diseases and are generally classified into small vessel diseases, such as those involving the eyes, kidneys, and nerves (microvascular disease), and large vessel diseases involving the heart and blood vessels (macrovascular disease). Diabetes accelerates the hardening of the arteries (atherosclerosis) of the larger blood vessels, leading to coronary heart disease (angina or heart attack), strokes, and pain in the lower extremities because of a lack of blood supply (claudication).
The major eye complication of diabetes is called diabetic retinopathy. Diabetic retinopathy occurs in patients who have had diabetes for at least five years. Diseased small blood vessels in the back of the eye cause the leakage of protein and blood in the retina. Disease in these blood vessels also causes the formation of small aneurysms (microaneurysms), and new but brittle blood vessels (neovascularization). Spontaneous bleeding from the new and brittle blood vessels can lead to retinal scarring and retinal detachment, thus impairing vision.
To treat diabetic retinopathy, a laser is used to destroy and prevent the recurrence of the development of these small aneurysms and brittle blood vessels. Approximately 50% of patients with diabetes will develop some degree of diabetic retinopathy after 10 years of diabetes, and 80% retinopathy after 15 years of the disease. Poor control of blood sugar and blood pressure further aggravates eye disease in diabetes.
Cataracts and glaucoma are also more common among diabetics. It is also important to note that since the lens of the eye lets water through if blood sugar concentrations vary a lot, the lens of the eye will shrink and swell with fluid accordingly. As a result, blurry vision is very common in poorly controlled diabetes. Patients are usually discouraged from getting a new eyeglass prescription until their blood sugar is controlled. This allows for a more accurate assessment of what kind of glasses prescription is required.
Kidney damage from diabetes is called diabetic nephropathy. The onset of kidney disease and its progression are extremely variable. Initially, diseased small blood vessels in the kidneys cause the leakage of protein in the urine. Later on, the kidneys lose their ability to cleanse and filter blood. The accumulation of toxic waste products in the blood leads to the need for dialysis. Dialysis involves using a machine that serves the function of the kidney by filtering and cleaning the blood. In patients who do not want to undergo chronic dialysis, kidney transplantation can be considered.
The progression of nephropathy in patients can be significantly slowed by controlling high blood pressure, and by aggressively treating high blood sugar levels. Angiotensin converting enzyme inhibitors (ACE inhibitors) or angiotensin receptor blockers (ARBs) used in treating high blood pressure may also benefit kidney disease in patients with diabetes.
Nerve damage from diabetes is called diabetic neuropathy and is also caused by disease of small blood vessels. In essence, the blood flow to the nerves is limited, leaving the nerves without blood flow, and they get damaged or die as a result (a term known as ischemia). Symptoms of diabetic nerve damage include numbness, burning, and aching of the feet and lower extremities. When the nerve disease causes a complete loss of sensation in the feet, patients may not be aware of injuries to the feet, and fail to properly protect them. Shoes or other protection should be worn as much as possible. Seemingly minor skin injuries should be attended to promptly to avoid serious infections. Because of poor blood circulation, diabetic foot injuries may not heal. Sometimes, minor foot injuries can lead to serious infection, ulcers, and even gangrene, necessitating surgical amputation of toes, feet, and other infected parts.
Diabetic nerve damage can affect the nerves that are important for penile erection, causing erectile dysfunction (ED, impotence). Erectile dysfunction can also be caused by poor blood flow to the penis from diabetic blood vessel disease.
Diabetic neuropathy can also affect nerves in the stomach and intestines, causing nausea, weight loss, diarrhea, and other symptoms of gastroparesis (delayed emptying of food contents from the stomach into the intestines, due to ineffective contraction of the stomach muscles).
The pain of diabetic nerve damage may respond to traditional treatments with certain medications such as gabapentin (Neurontin), phenytoin (Dilantin), and carbamazepine (Tegretol) that are traditionally used in the treatment of seizure disorders. Amitriptyline (Elavil, Endep) and desipramine (Norpraminine) are medications that are traditionally used for depression. While many of these medications are not indicated specifically for the treatment of diabetes-related nerve pain, they are used by physicians commonly.
The pain of diabetic nerve damage may also improve with better blood sugar control, though unfortunately blood glucose control and the course of neuropathy do not always go hand in hand. Newer medications for nerve pain include Pregabalin (Lyrica) and duloxetine (Cymbalta).
What can prevent diabetes complications?
Findings from the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) have clearly shown that aggressive and intensive control of elevated levels of blood sugar in patients with type 1 and type 2 diabetes decreases the complications of nephropathy, neuropathy, retinopathy, and may reduce the occurrence and severity of large blood vessel diseases. Aggressive control with intensive therapy means achieving fasting glucose levels between 70-120 mg/dl; glucose levels of less than 160 mg/dl after meals; and near normal hemoglobin A1c levels (see below).
Studies in type 1 patients have shown that in intensively treated patients, diabetic eye disease decreased by 76%, kidney disease decreased by 54%, and nerve disease decreased by 60%. More recently the EDIC trial has shown that type 1 diabetes is also associated with increased heart disease, similar to type 2 diabetes. However, the price for aggressive blood sugar control is a two to threefold increase in the incidence of abnormally low blood sugar levels (caused by diabetes medications). For this reason, tight control of diabetes to achieve glucose levels between 70 to120 mg/dl is not recommended for children under 13 years of age, patients with severe recurrent hypoglycemia, patients unaware of their hypoglycemia, and patients with far advanced diabetes complications. To achieve optimal glucose control without an undue risk of abnormally lowering blood sugar levels, patients with type 1 diabetes must monitor their blood glucose at least four times a day and administer insulin at least three times per day. In patients with type 2 diabetes, aggressive blood sugar control has similar beneficial effects on the eyes, kidneys, nerves, and blood vessels.
What is the prognosis for diabetes?
The prognosis of diabetes is related to the extent to which the condition is kept under control to prevent the development of the complications described in the preceding sections. Some of the more serious complications of diabetes such as kidney failure and cardiovascular disease can be life-threatening. Acute complications such as diabetic ketoacidosis can also be life-threatening. As mentioned above, aggressive control of blood sugar levels can prevent or delay the onset of complications, and many people with diabetes lead long and full lives.
Health Solutions From Our Sponsors
Centers for Disease Control and Prevention. "Diabetes."
Centers for Disease Control and Prevention. "National Diabetes Statistics Report."
Khardori, R., MD. "Type 2 Diabetes Mellitus." Medscape. Oct 23, 2019.
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Common Medical Abbreviations & Terms
Doctors, pharmacists, and other health-care professionals use abbreviations, acronyms, and other terminology for instructions and information in regard to a patient's health condition, prescription drugs they are to take, or medical procedures that have been ordered. There is no approved this list of common medical abbreviations, acronyms, and terminology used by doctors and other health- care professionals. You can use this list of medical abbreviations and acronyms written by our doctors the next time you can't understand what is on your prescription package, blood test results, or medical procedure orders. Examples include:
- ANED: Alive no evidence of disease. The patient arrived in the ER alive with no evidence of disease.
- ARF: Acute renal (kidney) failure
- cap: Capsule.
- CPAP: Continuous positive airway pressure. A treatment for sleep apnea.
- DJD: Degenerative joint disease. Another term for osteoarthritis.
- DM: Diabetes mellitus. Type 1 and type 2 diabetes
- HA: Headache
- IBD: Inflammatory bowel disease. A name for two disorders of the gastrointestinal (BI) tract, Crohn's disease and ulcerative colitis
- JT: Joint
- N/V: Nausea or vomiting.
- p.o.: By mouth. From the Latin terminology per os.
- q.i.d.: Four times daily. As in taking a medicine four times daily.
- RA: Rheumatoid arthritis
- SOB: Shortness of breath.
- T: Temperature. Temperature is recorded as part of the physical examination. It is one of the "vital signs."
Creatinine Blood TestCreatinine is a chemical waste molecule that is generated from muscle metabolism. Creatinine is produced from creatine, a molecule of major importance for energy production in muscles. Creatinine has been found to be a fairly reliable indicator of kidney function. As the kidneys become impaired the creatinine level in the blood will rise. Normal levels of creatinine in the blood vary from gender and age of the individual.
Diabetes QuizTake the Diabetes Quiz and learn the causes, signs, symptoms, and types of this growing epidemic. What does diabetes have to do with obesity and diet? Learn about life as a diabetic.
Exercises for Diabetes Nerve PainLearn how to cope with the symptoms of diabetic peripheral neuropathy through pain management exercises. Find relief for diabetic nerve pain without medication.
Diabetic Retinopathy PictureDiabetic retinopathy, a common complication of diabetes, affects the blood vessels in the retina (the thin light-sensitive membrane that covers the back of the eye). See a picture of Diabetic Retinopathy and learn more about the health topic.
Ferritin Blood Test (Normal, High, Low, Levels)Ferritin is a protein in the body that is used to store iron. The ferritin blood test can detect elevated or low levels of ferritin in the body, which may indicate disease such as hemochromatosis, rheumatoid arthritis, certain cancers, anemia, or iron deficiency.
CAD SlideshowWhat is heart disease (coronary artery disease)? Learn about the causes of heart disease, arrhythmias and myopathy. Symptoms of heart disease include chest pain and shortness of breath. Explore heart disease diagnosis, treatment, and prevention.
Heart Disease: Causes of a Heart AttackHeart disease prevention includes controlling risk factors like diet, exercise, and stress. Heart disease symptoms in women may differ from men. Use a heart disease risk calculator to determine your heart attack risk.
Hemoglobin A1c TestHemoglobin A1c or HbA1c is a protein on the surface of red blood cells. The HbA1c test is used to monitor blood sugar levels in people with type 1 and type 2 diabetes over time. Normal HbA1c levels are 6% or less. HbA1c levels can be affected by insulin use, fasting, glucose intake (oral or IV), or a combination of these and other factors. High hemoglobin A1c levels in the blood increases the risk of microvascular complications, for example, diabetic neuropathy, eye, and kidney disease.
Kidney (Renal) Failure
Kidney failure can occur from an acute event or a chronic condition or disease. Prerenal kidney failure is caused by blood loss, dehydration, or medication. Some of the renal causes of kidney failure include sepsis, medications, rhabdomyolysis, multiple myeloma, and acute glomerulonephritis.
Post renal causes of kidney failure include bladder obstruction, prostate problems, tumors, or kidney stones.Treatment options included diet, medications, or dialysis.
Metabolic Syndrome QuizMetabolic syndrome is serious and you should be concerned. Learn the causes, symptoms, treatments, and complications of metabolic syndrome with our quick quiz.
Triglycerides (Tests and Lowering Your Triglyceride Levels)Triglycerides are a common form of fat that we digest. Triglycerides are the main ingredient in animal fats and vegetable oils. Elevated levels of triglycerides are a risk factor for heart disease, heart attack, stroke, fatty liver disease, and pancreatitis. Elevated levels of triglycerides are also associated with diseases like diabetes, kidney disease, and medications (for example, diuretics, birth control pills, and beta blockers). Dietary changes, and medication if necessary can help lower triglyceride blood levels.
Type 2 Diabetes QuizWhat causes type 2 diabetes? Can it be prevented? Take this online quiz and challenge your knowledge of this common condition. Also, get the truth about myths and facts!
Type 2 Diabetes SignsLearn about type 2 diabetes warning signs, symptoms, diagnosis, and treatment options. Find out why thirst, headaches, and infections could be signs of diabetes. Discover the treatment options for people with type 2 diabetes, including medicines and lifestyle improvements.
Urinalysis (Urine Test)Urinalysis (urine test, drug test) is a test performed on a patient's urine sample to diagnose conditions and diseases such as urinary tract infection, kidney infection, kidney stones, and inflammation of the kidneys, or screen for progression of conditions such as diabetes and high blood pressure.